linux-kernel - Re: [PATCH v1 5/5] kvfree_rcu: Fix comments according to current code

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Message-ID: <20210503193413.GA2421@pc638.lan>
Date:   Mon, 3 May 2021 21:34:13 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     "Uladzislau Rezki (Sony)" <urezki@...il.com>,
        LKML <linux-kernel@...r.kernel.org>, RCU <rcu@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Daniel Axtens <dja@...ens.net>,
        Frederic Weisbecker <frederic@...nel.org>,
        Neeraj Upadhyay <neeraju@...eaurora.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Theodore Y . Ts'o" <tytso@....edu>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>
Subject: Re: [PATCH v1 5/5] kvfree_rcu: Fix comments according to current code

> On Wed, Apr 28, 2021 at 03:44:22PM +0200, Uladzislau Rezki (Sony) wrote:
> > We used to have an "emergency path" and comments related
> > to it. According to current kvfree_rcu() design that path
> > is not considered as emergency anymore.
> > 
> > This patch rephrases and updates comments regarding this.
> > 
> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> 
> Queued as follows, thank you!  Please check my usual wordsmithing to
> make sure that I did not mess anything up.
> 
> 							Thanx, Paul
> 
> ------------------------------------------------------------------------
> 
> commit 06c2113c4b1ce9ded69cd0ac4da9a00ed6be8834
> Author: Uladzislau Rezki (Sony) <urezki@...il.com>
> Date:   Wed Apr 28 15:44:22 2021 +0200
> 
>     kvfree_rcu: Fix comments according to current code
>     
>     The kvfree_rcu() function now defers allocations in the common
>     case due to the fact that there is no lockless access to the
>     memory-allocator caches/pools.  In addition, in CONFIG_PREEMPT_NONE=y
>     and in CONFIG_PREEMPT_VOLUNTARY=y kernels, there is no reliable way to
>     determine if spinlocks are held.  As a result, allocation is deferred in
>     the common case, and the two-argument form of kvfree_rcu() thus uses the
>     "channel 3" queue through all the rcu_head structures.  This channel
>     is called referred to as the emergency case in comments, and these
>     comments are now obsolete.
>     
>     This commit therefore updates these comments to reflect the new
>     common-case nature of such emergencies.
>     
>     Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
>     Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
> 
Looks good to me.

--
Vlad Rezki